Table 1.

The list of members in the Chlamydiaceae family, and the diseases caused by each species in their primary host and human. PID: pelvic inflammatory disease.

Species	Primary Host	Diseases in Primary Host	Transmission to Human
C. abortus	Small ruminants e.g., sheep and goats	Abortion in late gestation or deliver weak/dead fetus [3]	Possible though close contact with infected tissues, causes abortion, stillbirth, gestational septicaemia, PID, and atypical pneumonia [4,5,6,7,8,9]
C. avium	Avian e.g., pigeons and psittacine birds	Respiratory disease in psittacine birds and pigeons [10,11,12,13]	Unknown
C. caviae	Guinea pigs, cat, dogs, rabbits, and horses	Conjunctivitis and urogenital tract infections [14,15,16]	Possible though close contact, causes mild conjunctivitis, severe community-acquired pneumonia [14,17,18]
Ca. C. corallus	Snakes	Unknown	Unknown
C. felis	Felines, especially cats, and dogs	Conjunctivitis with minimal respiratory disease, and upper reproductive tract infections [19,20]	Possible cause of conjunctivitis in human [21]
C. gallinacea	Domestic poultry e.g., chickens, ducks, guinea fowls, turkeys	Reduced body weight [22]	Possible cause of atypical pneumoniae [13,23]
Ca. C. ibidis	Feral sacred ibis	Unknown	Unknown
C. muridarum	Rodents e.g., mouse, and chickens	Cervicovaginal infection, oviduct occlusion, hydrosalpinx formation in female mice [24,25]	-
C. pecorum	Koala, livestock species including cattle, sheep, goats, water buffalos, swine, bandicoots, and pigeons	Pneumonia, conjunctivitis, blindness, urinary incontinence, cystitis, nephritis, abortion, infertility, polyarthritis, sporadic bovine encephalomyelitis, and enteritis [26,27,28,29,30,31,32]	Unknown
C. pneumoniae	Human and a wide range of non-human mammals and reptiles encompassing koalas, horses, bandicoots, snakes, iguanas, chameleons, frogs, and turtles	Humans: Community-acquired pneumonia, reactive arthritis, chronic obstructive pulmonary disease, and pharyngitis [33,34,35,36,37,38,39,40,41,42] Implicated in the onset and progression of asthma, primary biliary cirrhosis, atherosclerosis, reactive arthritis, and lung cancer [34,35,43,44,45,46,47,48,49] Animals: Largely undescribed. Infected koalas exhibit signs related to respiratory disease that encompass sneezing, coughing, chest congestion, difficulty in breathing, rhinitis, as well as nasal discharge [50]	Unknown. However, the discovery of animal genotypes of C. pneumoniae in humans suggests a likelihood for zoonotic transmission [51,52]
Ca. C. sanzinia	Snake	Unknown	Unknown
C. psittaci	Avian	Psittacosis/ornithosis conjunctivitis, rhinitis, and blepharitis [53,54]	Possible through inhalation; causes fever, chills, headache, myalgia, and malaise with or without respiratory symptoms [55]
C. trachomatis	Human	Males: Non-gonococcal urethritis, prostatitis, epididymitis, epididymis orchitis, as well as seminal vesiculitis [56,57,58,59,60]. Likely role in infertility due to evidence of reduced semen volume, apoptosis of spermatozoa, and sperm DNA fragmentation following infection [61,62,63,64,65] Females: Mucopurulent cervicitis, urethritis, and salpingitis [56,59,60]. Adverse obstetrics and gynecological complications including salpingitis or PID, ectopic pregnancy, tubal factor infertility (TFI), preterm delivery, premature rupture of membranes, and spontaneous abortion [66,67,68,69,70,71,72]. Exposure of infants to the bacterium can cause conjunctivitis and lower respiratory tract infection in newborns [73,74]. Fitz-Hugh-Curtis syndrome [75,76,77]. Cervical and ovarian cancer [78,79]. Both sexes: Trachoma [80,81] Lymphogranuloma venereum (LGV) [82,83] Reactive arthritis [34,35]	-
C. serpentis	Snakes	Unknown	Unknown
C. suis	Swine	Respiratory disorders [84], conjunctivitis [85], enteritis [86], and reproductive failure	Possible through close contact, no reported symptoms [87,88,89]